1) Field of the Disclosure
The disclosure relates to aircraft insulation systems. In particular, the disclosure relates to aircraft insulation systems and methods having heat seal seams and/or fire penetration resistant coverings.
2) Description of Related Art
Many aircraft employ insulation blankets to moderate the interior temperature of the aircraft and to provide noise insulation. Such insulation blankets typically provide thermal and acoustic insulation and are placed into the air space or cavity between the aircraft fuselage skin panels and the aircraft interior panels. It is also desirable for such insulation blankets to incorporate fire resistant materials to protect passengers of an aircraft in the event of a fire such as a ground fuel fire or post-crash fire. The longer it takes for the fire to penetrate the aircraft fuselage, the more time aircraft passengers may have to evacuate the aircraft before being overcome by smoke or heat from the fire. Thus, an extended period of burnthrough protection for insulation blankets is desirable.
The Federal Aviation Administration (FAA) has promulgated regulations, contained in part, in 14 C.F.R. Section 25.856 (a) & (b), and part VII of Appendix F to 14 C.F.R. Section 25, requiring thermal and acoustic insulation blanket systems in commercial aircraft to provide improved burnthrough protection and flame propagation resistance in certain areas of airplanes. For example, FAA regulation 25.856(b) applies to thermal/acoustic insulation installed in the “lower half of the airplane fuselage”, which means the area below a horizontal line that bisects the cross section of the fuselage as measured with the airplane in a normal attitude on the ground. In addition, the FAA has issued Advisory Circular AC Number 25.856-2A, to provide guidance for a test method to determine burnthrough resistance of thermal and acoustic insulation materials installed in the lower half of the fuselage in transport category aircraft. The FAA 14 C.F.R. Section 25.856(b), in part, requires that a fire penetration resistant material in a thermal and acoustic insulation blanket system withstand a post-crash fuel fed fire of 1900 degrees Fahrenheit from penetrating into the passenger cabin or cargo compartment of an aircraft for at least four minutes (also referred to as “the Burnthrough Rule”).
Known thermal and acoustic insulation blanket systems typically include thermal and acoustic insulation blankets encapsulated within a film covering or bag. FAA burnthrough regulations primarily affect the contents of the insulation systems bags, and the FAA flame propagation resistance regulations primarily affect the film coverings used to fabricate the bags. The film coverings typically are used as a layer or covering, for example, layered between, laid over, or laid behind layers of thermal and acoustic insulation material, or as a covering or bag for partially or totally encapsulating one or more layers of thermal and acoustic insulation material.
Insulation blankets incorporating fire resistant materials are known. Such known insulation blankets may consist of one or multiple layers of fiberglass batting encapsulated by two layers of polymer film. The inboard and the outboard films may be heat sealed on the periphery to create a water tight seal. Multiple insulation blankets may then be taped together to create an assembly. However, the materials on such known insulation blanket assemblies, as well as the tape design, do not comply with the FAA regulation. In addition, the use of tape with known insulation blankets on an airplane can increase the overall weight of the airplane.
Accordingly, there is a need for an aircraft insulation system and method having heat seal seams and/or fire penetration resistant coverings that provides advantages over known systems and methods.